PREPARATION AND OPTICAL-PROPERTIES OF CDS-MICROCRYSTALLITES DEPOSITED IN POROUS VYCOR GLASS

CdS-microcrystallites were prepared in porous Vycor glass (PVG) by impregnation of PVG with an aqueous solution of Cd(NO3)2.4H2O and subsequent reaction with H2S gas. The optical absorption edge of the CdS/PVG containing 1.0 wt% cadmium exhibited a blue shift by 0.37 eV compared to bulk CdS, indicating the quantum size effect. The blue shift decreased with increasing diameter of CdS-microcrystallites in PVG. In the photoluminescence spectra of the CdS/PVG, the band-edge emission and the deep-level emission were observed. In accordance with the optical absorption spectra, the blue-shifted band-edge emission was also observed. The deep-level emission was effectively quenched by heating the CdS/PVG up to 300-degrees-C in air or by addition of methyl viologen (MV2+) as an electron acceptor, suggesting that the emission arose from electron-hole pair recombination on the surface of CdS-microcrystallites.